Wehnelt-cathode



Patented sq. 1, 1931 1,821,359

UNITED STATES PATENT OFFICE ENG-BEBE. HABHEN BEERINK AND J'OEANNES GIJ'SBEETU'S WILHELI mu, 0] EINDHOVEN, NETHERLANDS, ASSIGNORS 1'0 RADIO QOBPOBATION OI AIERIGA, A CORPORATION OF DELAWARE WEHNELT-CATHODE No Drawing. -App1icati0n fled April 4, 1929, Serial No. 352,597, and in the Ietherluds April 18, 1988.

The invention concerns cathodes, more particularly, Wehnelt-cathodes, and the process of manufacturing the same, and has for its object the provision of a cathode havl ing long life. As is known, a Wehnelt-cathode contains metallic compounds, such as oxides, which when heated emit electrons.

In our invention, the Wehnelt-cathode contains, in addition to the active emitting compound consisting, for example, of barium or a barium compound, a beryllium compound, preferably beryllium oxide. This has been found to increase the life of the cathode. Particular] good results are obtained by adding am a zirconium compound, preferab y zirconium oxide. A cathode which, ,in addition to the active emitting compound, contains both a beryllium and a zirconium compound, has proved I so to possess better emitting and lasting properties than a cathode which contains only a beryllium compound or only .a zirconium. compound.

Such a Wehnelt-cathode can be manufactured by coating a core with a suspension of barium carbonate, beryllium carbonate, zirconium oxide, and if desired, an agglutinant, e. g. arabic, and by subsequently heating t e body, preferably in a vacuum, and

30 preferably to a temperature of about 1000 C. The core may, for example, be anickel wire, or a tun 11 wire having helically wound on it a mckel wire.

I claim:

A process of manufacturing a Wehneltcathode, in which the core is coated with a sus nsion of barium carbonate, beryllium car onate, zirconium oxide and an agglutinant, and is subsequently heated in a vacuum.

ENGBER'I' BAR-Eli REERINK. JOHAIINES GIJSIERTUS ILIIELM MULDER. 

